1. Field of the Invention
The present invention relates to power dissipation reduction in a low noise amplifier (LNA) of a receiver.
2. Discussion of the Related Art
Low noise amplifiers (LNAs) are common components of receivers used in communication systems. For an LNAs with a fixed supply voltage, a conventional method for reducing power dissipation re-uses the currents in the LNA's stages (i.e., staging one stage on top of another stage). Because the currents are reused, the total DC power dissipation by the amplifier is reduced. In some cases, however, such power dissipation schemes are not acceptable; designers are then forced to “over-design” the LNA, requiring a higher, fixed DC power dissipation. In the detailed description below, the terms “P1 dB” and “IP3” are used. “P1 dB” or “1 dB compression point,” refers to a figure-of-merit used in amplifier design which indicates the power level that causes the gain to drop by 1 dB from its small signal value. A higher P1 dB indicates a higher power. IP3, or the third order intercept point, is a figure-of-merit for an amplifier's linearity or distortion. A higher IP3 value indicates greater linearity and less distortion.
The prior art fails to operate correctly when strong interference is present and dissipates higher DC power than required.